Protection of bodies for sandblasting ornamentation



Feb. 1, 1938. R. H. KAVANAUGH 2,106,979

PROTECTION OF BODIESl FOR SANDBLASTING ORNAMENTATION Filed March 20, 1936 Wl/ML@ PaienieaFeb. 1, 193s I Y 2,106,979l

UNITED STATES PATENT oF-Flcf:I

PROTECTION OF BODIES FOR SANDBLAST- i ING ORNAMENTATION Robert H. Kavanaugh, Brewer, Maine Appucationmcrcn 2o, 193s, serial No. 69,849-

13 claims. (ci. 4139) This invention relates to ornamentation by it includes new compositions especially intended sand blasting of the surface of bodies and artiand adapted for such treatment. cles -of various characteristics made .of diierent In the drawing furnished herewithv materials, such as stone,` wood, glass, etc. In Fig. 1 shows in perspective a body of which the thus ornamenting such articles it has been comsurface is to be ornamented, and a protective mon to apply and adhesively secure a stencil of under coating applied to such surface, a portion sand blast resistant material to the surfaces to of the under coating being broken away; be urna-mented, whereby only those portions of Fig. 2 isa View similar to Fig. 1 showing an such a surface which appear through the aperouter coating or layer of sand blast resistant matures of the stencil are attacked'and out away by terial over the under coating. and Showing also 10 the sand blast. p by dotted lines markings on'the resistant mate,

The stencils heretofore generally used in comrial indicating the lines on which the resistant merciai practice are made of compositions in material 1S t0 be Cut t0 make 8. Stencil; which glue is a principal ingredient, and in which Fig. 3 is a View similar to Figs. 1 and 2 showare contained also other substances, such as ing the stencil produced by cutting away por- 15 glycerine and powdered soft material (Whiting, tions of the layer of resistant material, and showstarch or the like) to give greater pliability and i118 also the eect 0f a Sand blast 0n the ornaless adhesiveness than is possessed by unmodimented body; l ed glue when dry. T he stencil material may be Fig. 4 iS a GIOSS Section 0n 1111 4-4 0f F18- 2;

applied in sheet form, after being softened by Fg- 5 1S 8 CTOSS SECOI! 0n 1111 5--5 0f F153; 20

moisture and heat, or it may be applied in ,a l Fig. 6 is a perspective View ShOWing the ornamass of 'putty-like consistency and spread in a mented body after removal 0f the Stencil and thick layer over the surface to be ornamented. Under Coating; l The-designs to be cut by sand blasting, or to be Fig- 7 1S 8f Section 0f the Ornamented body 1efi in raised relief against a sunken background, Showing the Same after removal 0f the Stencil 25 are cut in the Stencil matrial and the parts of but before removal o! such portions of the under the incised layer over the areas intended to be coating as remain when the stencil has been aected by the sand blast are removed. Stripped oi;

These stencil materials adhere with great te- Figa is a fragmentary Sectmm'l View show' nacity to surfaces of stone and wood and frethe operation of removing the under coat' 30 quently tear away4 bers from wood surfaces or mg?) pull out flakes of ,mica from granite, when Fig 9 is a' fragmentary section of a' body hav' stripped from such surfaces. They leave stains ing an under coatmgcomposed of a' mummy of on wood and other porous surfaces, and also on layers applied thereon preparatury' to applica" stones if allowed toremain too long, which are very dillcult to remove. Y

My object is to protect the surfaces to which ssi zrisraiziizzisft?,im use f,mmenimi.imnaees tate the removal of the stencils, boththe parts palrewchgy ocridaelsllgnguhrsame 40 thereof y which are cut out and stripped of! be- In the drawing H represents a. body of'any fore sand blasting, and the remaining parts after character of Whic'h it is intended u', ornament a they have served their purpose of protecting the .surface by Sand blastingb Such body may be of omamented Surface from impingement 0f grains' granite, marble or other stone, glass, tile, metal, 45 of sand. It is a part of this object to aord such wood, or any other material which is capable of protection by an under coat which can be easily being gut and 'abraded vby the impact -at high removed after it has served its purposefand has velocity of minerai particles such as grains of littleor no liability of staining or. discoloring san@ The mst and fundamental step in my @Ven the most'delicate surfaces of wood and present invention vis to coat the surface to be 50 stone. The invention comprises a treatment of ornament-,ed with a nlm (which forV the purposes ,Surfaces to be vrnamente prior to the applicaof the present disclosure I call an under coating) tion thereto of stencils or stencil materials; it which has adhesive properties suilicient to. hold comprises the combination with such treatment it in place on the surface to which it is applied Fig. 10 is a fragmentary elevation and Fig. 11 a sectionV on line Ii-II of Fig. 10 showing an extension of the comprehensive method to the of other steps in sand blast ornamentation; and during the sand blast operation; but will not in- 55 ltion of the ystencil'layer; 35'

jure the surface to which it is applied as frelquently do the glue compositions heretofore liquid, or at least suiilciently uid to be capable of application in a thin film by brushing, spraying or dipping, and can dry into a solid state having cohesive'strength approximately as great, and preferably greater than, the strength of its adhesive attachment to bodies of the nature indicated above.

'Ihe material which I have found most suitable for formation of such an under coating is rubber latex. 'Ihe unmodied latex of commerce is suitable for most purposes, but I may use vulcanized latex, or either vulcanized or unvulcanized latex modied by the addition of gelatine, glue, gum arabic, glycerine or the like to enhance its adhesive properties, and/or a material to make it more readily disintegrable under the sand blast. Examples of such materials are soft powdered materials including Whiting, starch and the like, which give body to the compositions as well as making them friable; and hard mineral matter, in powdered or granular condition, such as fine sand and other substances which have similar properties of helping to break down the coating film when incorporated therein.

Illustrative formulas of modified latex compositionsr for these latter purposes are:

(1) 75% of commercial latex (solid content approximately 40%) with 25% by volume of a gelatine-water solution containing about 20% gelatine; l

(2) 90% of latex (solid content approximately 70%) with 10% of a gum arabic solution containing one part gum arabic and two parts water;

(3) 90% of latex (solid content approximately '10%) with 10% common glue solution consisting of one part ground glue dissolved in four parts water;

(4) A mixture containing about 3% of glycerine and the balance commercial latex of any suitable concentration; v

(5) Any of the foregoing mixtures, or unmodified latex, with the addition of 10% more or less of Whiting, starch, sand, or other powdered or granular material suitable for the purposes set forth.

Considerable variation from the percentages here given may be made without departure from the invention.

The latex, whether modified or not, may be somewhat concentrated, but not to such an extent as to prevent being spread or deposited in a coating of substantially uniform depth which, on drying, leaves a nlm commensurate in thickness with tissue paper. 'I'he thickness of the under lboating is material only tothe extent that, as :ubber is resistant to sand blast, the coating should be thin enough to offer minimum resistance and to be quickly out away when portions of the surface over which it has been spread are expod to a sand blast. But the under coating when dry should be continuous so as to protect the surface on which it has been applied from direct contact with the superposed adhesive stencil layer, or adhesive used to secure a stencil, at substantially all points.

'Ihe drawing shows such an under coating at I2 as applied to a surface I3 ofthe body il. -The freely fluid condition of the coating material when first applied causes it to conform intimately to the surface on which it is applied, but the solid contents do not penetrate below the surface of wooden bodies o'r other bodies and materials having permeability equal to or less than wood.

A sheet or layer I4 of stencil material is superposed over the under coating when the latter is partly or thoroughly dry. Such layer may be a preformed sheet, or it may be applied and spread in a plastic consistency resembling that of putty. It may be of any of the compositions including a large content of glue heretofore used formaking stencils resistant to sand blast, and held inplace by its own adhesiveness, or may be of other suitable material secured by an applied coat of adhesive. When applied as an imperforate sheet, the design to be cut by sand blasting is flrst,cut out of the sheet by a knife on lines such as are indicated by the dotted lines in Fig. 2, and the vuseless severed portions are stripped oil, leaving a stencil such as shown in Fig. 3. Or a previously cut stencil sheet may be similarly applied. Such sheetl or layer adheres to the under coating. Suitable strength of adhesion in various circumstances may be obtained by modifications of the latex Aunder coating material, as previously set forth. For instance, the glue or gum arabic addition is useful when the material to be ornamentedhas a very smooth surface or relatively non porous structure, such as glass or highly polished stone. On the other hand, in order to prevent too great adhesion of the resistant stencil to the under coat, the latter may be covered with a thin `intermediate coating of shellac, varnish, calcimine or other material suitable to form a parting layer. Or a coating 'of unmodiiied latex may be applied to an under coat of latex modified by the addition of an adhesive.

Fig. 9 shows the application of intermediate coats I5 and I6 of the nature indicated to the Aand splinters from a wood body, bits of mica from granite bodies, etc., leaving unsightly pits and depressions. Also, when applied directly to the surfaces to be ornamented, these materials often leave stains which are removable only with great difilculty and at considerable expense, and in some instances are indelible. ,When applied to wood they frequently have such effect as to `prevent a desired finish being given to the wood by application of dyesy and pigments. vSuch undesirable effects are prevented by the use of my under coating.

object to be ornamented is subjected, after plac yment of the stencil, to the action of a sand blast,which cuts away the areas exposed through the openings in the stencil, afterV first destroying such parts of the under coating as may be ex` posed through the stencil apertures. It is for the purpose of facilitating such destruction of the under coating that it is initially made as thin as possible, and is in some cases made more friable by the addition of soft powder. A

Sometimes in removing the cut out parts ofA a stencil layer, the under coating is in part stripped H with the waste pieces of the stencil sheet and in part left adhering to the body. When such a condition occurs, the areas from which the under coating has been stripped will be cut away lduring the time requiredto cut through the remaining parts of the under coating, and therefore cut more deeply. In order then to insure sinking the background to uniform depth, I may so far destroy the exposed under coating by action of a solvent that it offers no appreciable hindrance to complete disintejgration by the sand blast. A suitable solvent for under coating composed principally of rubber,

and is to be understood as typifyinggenericallyall suitable solvents.

v At the end oi the sand blasting operation, the surface ci the body is formed with more or less deep depressions il which constitute either a depressed design or the background of a design in relief. Then the stencil is stripped oi, leave ing-the body and its ornamental design 2u exposed. The under coating facilitates iinal remaval of the stencil and protects the ornamented body from discoloration thereby in the same way as described beiore 'with respect to the cut out parts oi the stencil.

' The dual step'is removal-of the adherent lm of under coating left after the stencil has been stripped o. This is accomplished mechanically by rubbing the lm with a rough cloth, such as burlap, backed up by the operators hand or nger. Fig. t shows illustratively an operator-s nnger 2i covered by a fragment 22 of cloth in the act of rubbing the nlm i2 into a. roli 23.

'line cohesive strength of the rubber lm `yis enough to cause the rubbing action to roll it up and pull it away from the ornamented surface, with a minimum of eort and time expenditure. Ordinarily this mechanical, action is sufficient to remove the 4hlm and all traces thereof; but in the cases of surfaces having crevices or cavities deep 'enough to conne parts of the coatingV nlm, such retained bits may be readily' removed by application of carbon tetrachloride, oil-*equivalent solvent, and brushing. It avoids the time,

labor and expense oi' cleaning necessitated by.`

use ci the prior art cements.

The fragments of the iilm in being mechanically removed are rubbed over the surface of the ornamented body and have a detergent eiiect in removing dirt from the surface. Carbon tetrachloride, when such is used, has a further' cleansing effect by its ability to dissolve and carry away matter not mechanically removed. It is sometimes desirable to mount bodies to 'be ornamented on a supporting backing and` to.

secure them adhesively to such a backing in a manner permitting them to be removed without danger of breakage and without injury or damag'eotherwise. Thcneedofdoingsoarisesparticularly in the case ot thin plates or slabs of wood lor glass .in the neighborhood of Y, inch to' Vinch thick. or other thin objects where the design is to becut completely through or very deeply into vthe plate. For this purpose the body der coating material. The coated back of the4 object is laid against a sheet 25 oi' thick rubber or equivalent iiexible material, which is supported by a board 2l or equivalent solid backing support during the sand blasting operation.

The thin' and more or less fragile article is resiliently supported when undergoing sand blasting by a backing to which it is adherently attached. The uniting film of late x rubber or its equivalent, which may contain a modifier of the character previously described; provides a suiiiciently drm bond for the purpose, but permits the backing sheet to be readily peeled from the ornamented object without deiacement or breakage even though the object be a thin and fragile plate. Such parts of the coating iilm as then remain on the back of the object are removed in the same manner as before described with respect to the under coating. lm von the face.

While in the ioregoing. description I have named rubber latex as the preferred principal material of my under coating, I wish to make it plainly understood that I do not limit the protection which I claim tothe use o! this material exclusively in carrying out the purposes of the invention. Natural rubber latex isi an aqueous dispersion of rubber, and I may also 'use artificial' dispersions of rubber and all substances analogous to rubber in their properties of coalescing in a continuous dim and of clinging to surfaces on which they have been applied in the dispersed condition. But I may also use rubber and rubber-like substances in other forms of liquid extension than .the emulsied form, such as so lcalled solutions of rubber. Still further, I may use in vequivalent embodiments of ,the process invention, othersubstances than rubber which have similar mechanical properties 'toi cohesion and adhesion. unimportant useful feature of the invention is the facility with which the under coat can be removed sitcr'it has served its purpose, by rubbing or pulling it off from the surface on which it had been applied. ',I'he reason for this facility of rmoval is, I behevethat the under coating nlm has substantial cohesive strength, which generaliy is greater than the strength ci its adhenon to extended surfaces of wood, stone, metal, etc.. and its adhesive attachment to such surfaces is less than that of the substances commonly classed as adhesives. Thus the hlm is readily loosened from the surface by rubbing, and when loosened at one point is readily peeled and stripped from adjacent points by rubbing and pulling. Rubber and substances and compositions which ihave properties similar to rubber in those particulars, although they may not be' chemically classiable as rubber. are included within the scope of the protection which I claim and within the meaning of the term rubber-like as used in this specification and in' 1. The method of'uniting'a stencil to a body to be ornamented by sand blasting which consistsinap .toasurfaceofthebodya coating of v inliquid extension and, after drying of such coating; adhesively securing the stencil to :ne Aresidual anno; the enum;l

2. The method of vprotecting 'a body for sand blast ornamentation which in applyingY to the surface of the body a coating of rubber in liquid suspension or solutlon,'allowing such coating to dry to a thin and substantially continuous film, and applying in adherent connection with such 111m a stencil layer.

3. The method of preparing a body for sand blast ornamentation which consists in spreading over the surface to be ornamented oi' such body a coating of material in liquid suspension or solution, which material has the capacity of coalescing into a substantially continuous coherent film upon drying of the liquid vehicle, and of then remaining in adherent connection with the /surface to which it has `been applied, with an adhesive bond of less strength than its coherent strength, and applying and adhesively connecting to such film a stencil sheet or layer of sand blast resistant material.

4. 'I'he method of ornamenting a body by sand blasting which consists in applyingto the surface'of such body an under coating and a stencil layer as set forth in claim 3, applying a solvent of the under coating material to such portion of the under coat as is exposed through an aperture of the stencil layer, and directing a sand blast against the body through such aperture.

`5. In the method of sand blasting ornamentation, the steps of preparing a body to be ornamented by placing thereon a lightly adherent film of material which has greater strength of cohesion than of adhesion tofthe body; adherently connecting a stencil to said film, sand blasting the body -through apertures of the stencil, stripping the stencil from the body, and removing such portion of the under film as thereafter adheres to the body, by rubbing or pulling it away.

6. In the method of sand blast ornamentation with the aid of an adhesive stencil applied to the surface to be ornamented, the step of protecting such surface from the stencil, which consists in placing on the surface beneath the stencil an under coat of material which is adherent to both the body and the stencil and has a cohesive strength greater than the strength of its adhesion to the body.

7. In the method of ornamenting stone, wood,

etc. by sand blasting with the aid of a stencil of sand blast resistant material having strongly adhesive properties with respect to stone, wood, etc; the step of protecting the surface to be carved from staining by such stencil and mechanical injury when the stencil substance is stripped oil', which consists in applying a fluid composed essentially of rubber latex so as to form an undercoat between such surface and the stencil.

8. In the method of ornamenting as set forth in claim 7, the step of forming a protective undercoat by applying rubber latex containing a minor -proportion of an adhesive substance in liquid phase.

9. In the method of ornamenting as set forth in claim 7, the step of forming a'protective undercoat by applying rubber latex containing an admixture of glycerine.

10.v In the method of ornamenting as set forth in claim 7, the step of forming apr'otective undercoat by applying rubber latex containing in an intimately mixed state, a content in the order of 10% of dry powdered materiah 11. In the method of ornamenting as set forth in claim 7, the step of forming a protective under` coat by applying rubber latex containing a minor content of glue dissolved in water.

12. In the method of ornamenting as set forth in claim 7, the step oi' forming a protective undercoat by applying rubber latex containing a minor content of gum arabic dissolved in Wa'- ter.

13. The method of protectingstone, wood, etc. from discoloration and mechanical injury due to the use of a stencil of sand blast resistant material having'strongly adhesive properties, which consists in applying a fluid composed essentially of rubber latex so as to form an undercoat between the surface of the stone, wood, etc. to be sand blasted, and the adhesive stencil.

ROBERT H. KAVANAUGH` 

